Color mixing optics for LED illumination device

Abstract

Illumination devices with improved color mixing optics are disclosed herein for mixing the colors produced by a multi-colored LED emitter module to produce uniform color throughout the entire beam angle of the output light beam, along with smoother edges and improved center beam intensity. Embodiments disclosed herein include a unique arrangement of multi-color LEDs within an emitter module, a unique exit lens with different patterns of lenslets on opposing sides of the lens, and other associated optical features that thoroughly mix the different color components, and as such, provide uniform color across the output beam exiting the illumination device. Additional embodiments disclosed herein include a unique arrangement of photodetectors within the primary optics structure of the LED emitter module that ensure the optical feedback system properly measures the light produced by all similarly colored emission LEDs.

What is claimed is: 
     
         1 . A light-emitting diode (LED) lamp, comprising:
 a parabolic reflector having a plurality of lunes that extend from an entrance having a first diameter an exit having a second diameter greater than the first diameter;   an exit lens having the second diameter disposed transversely across the exit of the parabolic reflector;   wherein the exit lens includes:
 a first plurality of lenslets disposed on a first surface of the lens internal to the parabolic reflector; and 
 a second plurality of lenslets disposed on a second surface of the lens, the second surface of the exit lens disposed transversely across a thickness of the exit lens from the first surface of the exit lens;
 wherein the first plurality of lenslets includes a lesser number of lenslets than the second plurality of lenslets; and 
 
   a plurality of LED strings arranged to form an LED array on a substrate, the substrate disposed at a focal point of the parabolic reflector.   
     
     
         2 . The LED lamp of  claim 1  wherein each of the lenslets included in the first plurality of lenslets is configured with an identical aperture shape. 
     
     
         3 . The LED lamp of  claim 2  wherein each of the lenslets included in the second plurality of lenslets is configured with an identical aperture shape. 
     
     
         4 . The LED lamp of  claim 3  wherein a center of each of the lenslets included in the second plurality of lenslets disposed on the second surface of the exit lens is aligned with a center of a respective lenslet included in the first plurality of lenslets. 
     
     
         5 . The LED lamp of  claim 4 , wherein the identical aperture shape of first plurality of lenslets and identical aperture shape of the second plurality of lenslets is a polygon having N sides, wherein Nis an even number greater than or equal to 4. 
     
     
         6 . The LED lamp of  claim 3 , wherein the first plurality of lenslets and the second plurality of lenslets each comprise a square aperture shape, and wherein an aperture ratio of the first plurality of lenslets to the second plurality of lenslets is 4:1. 
     
     
         7 . The LED lamp of  claim 3 , wherein the first plurality of lenslets and the second plurality of lenslets each comprise a hexagonal aperture shape, and wherein an aperture ratio of the first plurality of lenslets to the second plurality of lenslets is 3:1. 
     
     
         8 . The LED lamp of  claim 3 , wherein the first plurality of lenslets and the second plurality of lenslets each comprise a circular aperture shape, and wherein an aperture ratio of the first plurality of lenslets to the second plurality of lenslets is 3:1 or 4:1. 
     
     
         9 . The LED lamp of  claim 1 , wherein a curvature ratio of the first plurality of lenslets to the second plurality of lenslets is within a range of 1:10 to 1:9. 
     
     
         10 . The LED lamp of  claim 1 , wherein the exit lens is formed from a material having a refractive index within a range of about 1.45 to about 1.65. 
     
     
         11 . The LED lamp of  claim 1  wherein each of the plurality of LED strings produce a different output spectrum. 
     
     
         12 . The LED lamp of  claim 11  wherein the LED strings are arranged to form an N-sided polygonal array on the surface of the substrate. 
     
     
         13 . The LED lamp of  claim 12 , further comprising: a plurality of photodetectors that includes N photodetectors. 
     
     
         14 . The LED lamp of  claim 13  wherein each of the N photodetectors is disposed at a midpoint of each respective side of the N-sided polygonal array formed by the plurality of LED strings. 
     
     
         15 . The LED lamp of  claim 13 , further comprising an optical structure disposed on a surface of the substrate, wherein the optical structure encapsulates the plurality of LED strings and the plurality of photodetectors. 
     
     
         16 . The LED lamp of  claim 15  wherein the optical structure comprises a hemispherical dome.